THE MYTH OF THE ALL-IN-ONE CONVENIENCE

By Brian Frank

When it comes to deciding on the best way to consume fluids, calories, and electrolytes during extended exercise (2+ hours), perhaps you are one of the athletes who thinks, “I just want everything in one bottle” because it sounds convenient and means that you don’t have to think about fueling while you’re riding or running. Not surprisingly, this apparently logical approach has been heavily encouraged by companies selling “all-in-one” fueling products. They constantly tout the “convenience” of their all-in-one fuel product—“just drink this and you’ll be all set” they say.
 
My approach to fueling is 180 degrees opposite. I personally believe that the most effective way to fuel is by taking fluid (water), calories, and electrolytes separately and independent of each other. After you read my reasoning, I think you will agree that fueling using three separate “buckets,” as opposed to tossing everything in one “bucket,” is actually the most logical approach and guarantees the best possible outcome across the entire spectrum of conditions and applications you will encounter during 3, 6, 12, or more hours of continuous exercise.
The problem with combining your fluid, calories, and electrolytes into one container is that it will only meet your body’s needs in a very narrow set of temperature, duration, and intensity situations. I’ll illustrate my point by using an analogy of a single-speed bike vs. a 22-speed road bike. The single-speed bike represents the all-in-one fueling approach. This analogy excludes those of you who ride single-speed bikes for the added challenge—we’re only talking efficiency and maximum speed/minimum time from point A to point B here.
That single-speed bike will work great for you on relatively flat surfaces and at a speed that has you spinning between 70 and 100 rpm. But what happens when you encounter steep climbs or long descents? Now you are walking your bike up hill and coasting down due to your single gear option. The same is true with an all-in-one fuel. Single-speed bikes are cool, but for most of us, they have a pretty limited appeal and certainly would not be our choice if we were limited to owning only one bike. Same goes for the “all-in-one” fuel bottle—limited appeal and certainly not what I’d want my entire race to be dependent upon.
So, unless you always exercise in the exact same temperature and humidity (plus or minus five degrees and 5%, respectively) from start to finish, for no more than 2-3 hours, the all-in-one formula will leave you hanging every time.
Now consider the 22-speed bike. You can change gears to accommodate anything that comes your way—from short, steep climbs to long, grinding climbs, or long gradual descents—and still maintain maximum efficiency and pace. Thus, you have the same ability when you manage your fluid, calories, and electrolytes independently of each other and are able to make adjustments as conditions change. The flexibility afforded by separating the fueling components during extended hours of exercise is crucial since the temperature, humidity, terrain, and pace will undoubtedly change significantly between the time you start and when you finish.
To bring the concept home, let’s consider a typical iron distance triathlon, double century, 100-mile MTB, 50-mile trail race, or the like—basically 6–24 hours of continuous exercise. These events start in the early morning hours when it’s nice and cool and continue on through the hottest part of the day, and sometimes back down to cooling temperatures. 20–30 degree variances are typical, and you may encounter as much as 50-degree temperature differences.
During the first few hours when it’s still cool, your caloric intake should be at your optimal level (for me, that’s 130–150 calories per hour), while fluid intake will be well below your max and the need for electrolytes is minimal. However, as the heat intensifies and the body becomes increasingly depleted, you’ll need to reduce your hourly caloric intake (the body can process more calories in cool temps than in hot temps) while simultaneously increasing your fluid and electrolyte intake. These diverging needs can easily be met when you fuel separately. On the other hand, you cannot manage these changing requirements with an all-in-one fuel bottle.